Who did the united states believe was harboring the terrorists responsible for the september 11 attack?

iran
saudi arabia
pakistan
afghanistan

Afghanistan

Explanation:

The attacks of September 11, 2001 (commonly referred to as 9/11 or with the 11-S or 11S numeronym) were a series of four terrorist attacks committed on the morning of Tuesday, September 11, 2001, by 19 members of the jihadist network Al Qaeda, by hijacking commercial aircraft to be hit against various targets, causing the death of 3016 people (including the 19 terrorists and the 24 disappeared) and leaving more than 6000 injured, as well as the destruction in New York of the entire complex of buildings of the World Trade Center (including the Twin Towers) and serious damage to the Pentagon building (headquarters of the Department of Defense of the United States, in the state of Virginia), an episode that would precede the war in Afghanistan and the adoption by the US government and its allies of the so-called "war on terror" policy.